A jury on Friday found Daniel Marsh guilty of killing an elderly Davis couple -- and also of four special circumstances, including the use of a deadly weapon, multiple murders, lying in wait and torture.

The jury in Marsh's case -- Marsh is the teen who killed the couple as the pair slept in bed last year -- had just heard the final arguments Thursday.

Marsh was 15 when he murdered Northrup and Maupin on April 14, 2013. He was tried as an adult.

"I don't like to think of my father and Claudia being tortured," said James Northrup, son of Oliver Northrup. "And it was a unanimous conviction that he did torture them, and it's very hard to contemplate."

In their closing arguments Thursday, attorneys focused intensely on Marsh's mental state on the day of the killings.

Prosecutor Michael Cabral called the killings premeditated.

"He wanted to kill somebody, and he did," Cabral told jurors.

But Marsh's attorney, public defender Ron Johnson, said the teenager was not in control of his own thoughts or actions that day.

Johnson argued that Marsh, who had been receiving mental health treatment for years before the killings, was impacted by the side effects of drugs that gave him "morbid thoughts."

"I think that he is ill," Hurd said. "But I think that he knew exactly what he was doing, and I don't believe there's a treatment for that illness at this time. So, I think prison would feel really good for me and my family."

In a videotaped confession last year, Marsh told investigators he enjoyed killing the couple and found the experience exhilarating.

Marsh was accused of breaking into the couple's home. He said on tape that he stood over the couple as they slept in bed and then began stabbing them and mutilating their bodies.

"He stole two of the most beautiful people that I would ever hope to meet and love again in my lifetime," said Sherri Shaidell, a friend of the couple who was in the courtroom Thursday.